Machine Tool

ABSTRACT

The machine tool has a machine bed ( 10 ) having a first horizontal linear guide ( 1 ) and a second horizontal linear guide ( 2 ) arranged at right angles to the first linear guide ( 1 ). On the first linear guide ( 1 ) is arranged, in an axially displaceable manner, a workpiece clamping fixture ( 3 ), which is swivelable about a swivel axis ( 4 ) oriented parallel to the second linear guide ( 2 ) and is rotatable about a rotation axis ( 5 ) oriented at right angles to the swivel axis ( 4 ). On the second linear guide ( 2 ) a toque motor driven swivel arm ( 6 ) is axially displaceable, the swivel axis ( 7 ) of which is arranged parallel to the first linear guide ( 1 ) and which on its free end bears a tool spindle ( 8 ), the axis ( 9 ) of which is oriented parallel to the first linear guide ( 1 ).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit and priority of European PatentApplication No. 17 183 550.7, filed Jul. 27, 2017. The entire disclosureof the above application is incorporated herein by reference.

BACKGROUND Technical Field

The invention relates to a machine tool according to the preamble ofPatent Claim 1.

Related Art

Document EP1002621A1 shows a similarly constructed machine tool. Theswivel motion of the swivel arm is in this machine produced by a spindledrive and a lever mechanism.

SUMMARY

Starting from this prior art, an aspect of the invention is to propose amachine tool which is of simpler construction and allows more rapidswivel motions of the swivel arm than the known machine.

This aspect is achieved according to the invention by the featuresdescribed herein.

By virtue of the design according to the invention, the machine toolrequires for the swivel motion of the swivel arm fewer moving parts andallows more rapid swivel motions than the known machine.

Particular embodiments of the invention are also described.

Another aspect of the invention relates to a swivel arm for a machinetool and achieves the die object of damping vibrations of the swivel armwhich are caused, for instance, by the tool spindle disposed on its end.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are explained below withreference to the attached drawings, wherein:

FIG. 1 shows a perspective view of a machine tool according to theinvention;

FIG. 2 shows a similar view to FIG. 1 with X-Y protective walls and atool-holding chain magazine, and

FIG. 3 shows a sectional view of the mounting and of the drive mechanismof the swivel arm.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 shows in a perspective view an illustrative embodiment of themachine tool according to the invention. This is particularly suitablefor the machining of blade wheels for turbines, so-called “bladeddiscs”, also referred to as “bliscs”. On a machine bed 10 is arranged afirst horizontal linear guide 1 and, at right angles thereto, a secondhorizontal linear guide 2. On the first linear guide 1, a workpiececlamping fixture 3 is arranged such that it is horizontally movable andis swivelable about a horizontal swivel axis 4. For the horizontalmotion of the workpiece clamping fixture 3 on the first linear guide 1,a ball screw, for instance, is provided. Alternatively, the horizontalmotion can be executed by means of a linear motor. Moreover, theworkpiece clamping fixture 3 is rotatable about a rotation axis 5oriented at right angles to its swivel axis 4. Disc-shaped blanks forblade wheels are supplied lying flat, for instance on pallets. Thearrangement and design of the workpiece clamping fixture 3 allows theseblanks to be clamped without being tilted, which is particularlyadvantageous in the case of large and heavy blanks.

On the second linear guide 2, a swivel arm 6 is arranged such that it ishorizontally movable and is swivelable about a horizontal swivel axis 7,on the free end of which swivel arm is arranged a tool spindle 8. Thehorizontal motions of the swivel arm 6 on the second linear guide 2 arepreferably executed by a linear motor. The axis 9 of the tool spindle isoriented parallel to the swivel axis 7. The machine tool according tothe invention is thus a five-axis machine having the translatory axes X,Y and Z and the rotatory axes A and B. A particularity is here that, fora pure displacement of the tool along the Y-axis, a combined circularmotion of the tool spindle 8 and linear motion of the swivel axis 7along the linear guide 2 is necessary. A particular advantage of thisconstruction consists in the fact that the centre of gravity of theentire unit which is movable on the second linear guide 2 is locatedvertically only a little above the second linear guide 2 and moves onlya little upwards when the tool spindle 8 is transported into itsuppermost position. This in contrast to machine tools of differentconstruction, such as, for instance, the machine according to EP1509360,in which a tool spindle is likewise disposed on a swivel arm, wherein,however, the swivel arm is raised, together with its swivel drive, alonga vertical linear guide in order to bring the tool spindle into an upperposition. A high centre of gravity promotes the occurrence ofundesirable vibrations. The direct driving of the swivel arm 6 by atorque motor disposed on the swivel axis 7 allows rapid and precisemotions of the tool spindle 8.

FIG. 2 shows the same machine as FIG. 1, yet with additionalsub-assemblies, of which two are described in greater detail below. TwoX-Y protective covers 11 and 12 separate the working space from theother regions of the machine tool, in particular the linear guides 1 and2, in order to keep chips, and also coolant and lubricant, in theworking space. These X-Y protective covers can be of known construction,having a driving plate 13 and plate fins operatively connected thereto,for instance as described in EP19861324A1. In the machine according tothe invention, having the swivel arm 6, the problem now exists that thatpart of the tool spindle 8 which passes through the driving plate 13,with the swiveling of the swivel arm 6, inevitably in the driving plate13 executes a rotary motion. Therefore the tool spindle 8 cannot beconnected directly to the driving plate 8, but rather with theinterposition of a pivot bearing 14.

A further sub-assembly, which is visible in FIG. 2, is a tool-holdingchain magazine 15, which is of angular or arcuate configuration and isconfigured such that a limb 16 ends with an at least approximatelyhorizontally oriented end in the top of the work region, and a limb 17ends with an at least approximately vertically oriented end in a region,facing away from the working area, behind the first linear guide. In theend region of the limb 16 is arranged a tool changer 18, which isreachable by the tool spindle 8 along a short path. The end region ofthe limb 17 is configured for the loading and emptying of thetool-holding chain store 15 and is easily reachable by an operator.

FIG. 3 shows in a sectioned view a detail of the mounting of the swivelarm 6. The latter is driven in the present example by means of anexternal-rotor torque motor. A torque motor stator denoted by 19 has astator part 20 connected in a rotationally secure manner thereto. Atorque motor rotor 21 is additionally supported on the stator part 20 byan oil-lubricated slide bearing 22. The slide bearing 22 has, by virtueof its oil film, a vibration-damping effect (squeeze film damping).

What is claimed is:
 1. Machine tool comprising a machine bed (10) havinga first horizontal linear guide (1) and a second horizontal linear guide(2) arranged at right angles to the first linear guide (1), wherein onthe first linear guide (1) is arranged, in an axially displaceablemanner, a workpiece clamping fixture (3), which is swivelable about aswivel axis (4) oriented parallel to the second linear guide (2) and isrotatable about a rotation axis (5) oriented at right angles to theswivel axis (4), wherein on the second linear guide (2) a swivel arm (6)is axially displaceable, the swivel axis (7) of which is arrangedparallel to the first linear guide (1) and which on its free end bears atool spindle (8), the axis (9) of which is oriented parallel to thefirst linear guide (1), characterized in that the swivel arm (6) isswivelable by means of a torque motor disposed on its swivel axis (7).2. Machine tool according to claim 1, wherein, for the axialdisplacement of the workpiece clamping fixture (3) on the first linearguide (1) and/or the axial displacement of the swivel arm (6) on thesecond linear guide (2), a linear motor is present.
 3. Machine toolaccording to claim 1 wherein, for the swivel motion and the rotarymotion of the workpiece clamping fixture (3), a torque motor isrespectively present.
 4. Machine tool according to claim 1 whereinparallel to the second linear guide (2), on the side facing towards theworkpiece clamping fixture (3), is arranged an X-Y protective cover (11)having a driving plate (13) in which is accommodated a pivot bearing(14) surrounding the tool-side end of the tool spindle (8).
 5. Machinetool according to claim 1 wherein parallel to the second linear guide(2), on the side facing towards the workpiece clamping fixture (3), isarranged an angular or arcuate tool-holding chain magazine (15) havingan approximately horizontally arranged limb (16) and an approximatelyvertically arranged limb (17), and in that at the free end of theapproximately horizontal limb (16) is arranged a tool changer (18).
 6. Aswivel arm (6) for a machine tool comprising, a machine tool which isswivelable about a swivel axis (7) and bears on its free end a toolspindle (8), characterized in that the swivel arm (6) is directlydrivable by means of a torque motor (19, 20, 21), and a slide bearing(22) acting between the stator (20) and the rotor (21) is arranged withoil damping.
 7. Swivel arm (6) according to claim 6, wherein the torquemotor (19, 20, 21) has an external rotor (21) and an internal stator(19, 20).